Add jsonb_canonical()

Author: Nikita Glukhov

src/backend/utils/adt/jsonb.c

@@ -52,6 +52,13 @@ typedef enum					/* type categories for datum_to_jsonb */
 	JSONBTYPE_OTHER				/* all else */
 } JsonbTypeCategory;
 
+typedef enum
+{
+	JsonFormatCanonical,
+	JsonFormatNormal,
+	JsonFormatIndented
+} JsonFormat;
+
 typedef struct JsonbAggState
 {
 	JsonbInState *res;
@@ -86,7 +93,8 @@ static void datum_to_jsonb(Datum val, bool is_null, JsonbInState *result,
 						   bool key_scalar);
 static void add_jsonb(Datum val, bool is_null, JsonbInState *result,
 					  Oid val_type, bool key_scalar);
-static char *JsonbToCStringWorker(StringInfo out, JsonbContainer *in, int estimated_len, bool indent);
+static char *JsonbToCStringWorker(StringInfo out, JsonbContainer *in,
+								  int estimated_len, JsonFormat format);
 static void add_indent(StringInfo out, bool indent, int level);
 
 /*
@@ -431,7 +439,7 @@ jsonb_in_scalar(void *pstate, char *token, JsonTokenType tokentype)
 char *
 JsonbToCString(StringInfo out, JsonbContainer *in, int estimated_len)
 {
-	return JsonbToCStringWorker(out, in, estimated_len, false);
+	return JsonbToCStringWorker(out, in, estimated_len, JsonFormatNormal);
 }
 
 /*
@@ -440,14 +448,21 @@ JsonbToCString(StringInfo out, JsonbContainer *in, int estimated_len)
 char *
 JsonbToCStringIndent(StringInfo out, JsonbContainer *in, int estimated_len)
 {
-	return JsonbToCStringWorker(out, in, estimated_len, true);
+	return JsonbToCStringWorker(out, in, estimated_len, JsonFormatIndented);
+}
+
+char *
+JsonbToCStringCanonical(StringInfo out, JsonbContainer *in, int estimated_len)
+{
+	return JsonbToCStringWorker(out, in, estimated_len, JsonFormatCanonical);
 }
 
 /*
  * common worker for above two functions
  */
 static char *
-JsonbToCStringWorker(StringInfo out, JsonbContainer *in, int estimated_len, bool indent)
+JsonbToCStringWorker(StringInfo out, JsonbContainer *in, int estimated_len,
+					 JsonFormat format)
 {
 	bool		first = true;
 	JsonbIterator *it;
@@ -457,7 +472,8 @@ JsonbToCStringWorker(StringInfo out, JsonbContainer *in, int estimated_len, bool
 	bool		redo_switch = false;
 
 	/* If we are indenting, don't add a space after a comma */
-	int			ispaces = indent ? 1 : 2;
+	int			ispaces = format == JsonFormatNormal ? 2 : 1;
+	bool		indent = format == JsonFormatIndented;
 
 	/*
 	 * Don't indent the very first item. This gets set to the indent flag at

src/backend/utils/adt/jsonfuncs.c

@@ -4307,6 +4307,17 @@ jsonb_pretty(PG_FUNCTION_ARGS)
 	PG_RETURN_TEXT_P(cstring_to_text_with_len(str->data, str->len));
 }
 
+Datum
+jsonb_canonical(PG_FUNCTION_ARGS)
+{
+	Jsonb	   *jb = PG_GETARG_JSONB(0);
+	StringInfo	str = makeStringInfo();
+
+	JsonbToCStringCanonical(str, &jb->root, VARSIZE(jb));
+
+	PG_RETURN_TEXT_P(cstring_to_text_with_len(str->data, str->len));
+}
+
 /*
  * SQL function jsonb_concat (jsonb, jsonb)
  *

src/include/catalog/pg_proc.dat

@@ -9706,6 +9706,9 @@
 { oid => '3306', descr => 'Indented text from jsonb',
   proname => 'jsonb_pretty', prorettype => 'text', proargtypes => 'jsonb',
   prosrc => 'jsonb_pretty' },
+{ oid => '2137', descr => 'Canonical text from jsonb',
+  proname => 'jsonb_canonical', prorettype => 'text',
+  proargtypes => 'jsonb', prosrc => 'jsonb_canonical' },
 { oid => '3579', descr => 'Insert value into a jsonb',
   proname => 'jsonb_insert', prorettype => 'jsonb',
   proargtypes => 'jsonb _text jsonb bool', prosrc => 'jsonb_insert' },

src/include/utils/jsonb.h

@@ -373,6 +373,8 @@ extern char *JsonbToCString(StringInfo out, JsonbContainer *in,
 							int estimated_len);
 extern char *JsonbToCStringIndent(StringInfo out, JsonbContainer *in,
 								  int estimated_len);
+extern char *JsonbToCStringCanonical(StringInfo out, JsonbContainer *in,
+									 int estimated_len);
 extern bool JsonbExtractScalar(JsonbContainer *jbc, JsonbValue *res);
 extern const char *JsonbTypeName(JsonbValue *jb);